11-PhyD-3 Astrophysics

Put these objects in size order from the smallest.

• Planet

• Comet

• Galaxy

• Satellite

• Star

What is the reason a Main sequence star is so stable?

• The number of atoms remain the same

• The radiation pressure balances the pressure of weight

• Magnetic forces within it hold it together

• It has plenty of emotional support from it's friends

All stars begin their life in a

• Main Sequence
• Nebula
• Protostar
• Black Dwarf

Which of the following are in the correct order of size from largest to smallest?

• galaxy, universe, planet, star

• star, planet, comet, galaxy, moon

• galaxy, universe, star, planet, moon

• universe, galaxy, star, planet, comet

What object is at the centre of our Solar System?

• a black hole

• a large star

• the Earth

• a quasar

Stars are classified based on two properties of the star. Which of the following properties are the basis of classification?

• brightness and colour

• colour and surface temperature

• brightness and surface temperature

• size and colour

Where do stars form?

• They do not form – they have been here since the beginning of the Universe.

• They form in a supernova.

• They form in stellar nebulae.

• They form from dead planets

When a star is in the main sequence, what can be said about the forces acting inside the star?

• The outward pressure is greater than the gravitational pull.

• The gravitational pull is greater than the pressure from the fusion reactions.

• All the forces acting on the star are unbalanced.

• The inward gravitational attraction is equal to the outward pressure from the fusion reactions.

How might it be noticeable that a star is now fusing helium rather than hydrogen atoms?

• The star cools and becomes a white dwarf.

• The star shrinks then expands to form a red giant.

• A black hole is created.

• The star stops glowing.

Mars has a smaller gravitational field strength at the surface than the Earth. This is because...

• The mass of Mars is smaller than Earth.

• Mars has a very thin atmosphere.

• Mars has no water on the surface.

• Mars orbits the Sun at a slower speed than Earth.